When the ENT first said I had Chiari Malformation I didn't understand the words. So here, in layman's term I will try to explain what exactly is going on with my brain.
Basically my skull is too small for my brain. (hee hee!! I'm too smart for my own darn good! And I have MRI pictures to prove it!) And because my skull is too small it causes pressure at the back of my brain. Your brain is supposed to sit inside the skull. The cerebellar tonsils (yes, your brain has tonsils too) extend down through the base of my skull. So my brain stem is cramped. And the pressure causes a multitude of symptoms: headaches ranging from mild to extreme in the back of the skull; dizziness and nausea; blurred or haloed vision (without the acid trip); tingling in your hands and feet; tinnitus or ringing in your ears; numbness in your face; difficulty thinking cognitively; fatigue, sleeplessness and general malaise. More severe symptoms include seizures, a build-up of fluid inside the spinal cord (known as syrinx) and an assortment of other ailments. Fortunately I do not have the more severe symptoms.
Thus far my diagnosis is Chiari malformation with herniation between 6 - 7 mm. Yes, millimeters may not be very big, but think about it - your skull should hold 100 marbles, but only grew large enough for 99. The last marble is still there but is being squished at the back of your skull. Ouch.
So, in a nutshell, that's how I describe Chiari. For more information check out my links.